1. Field of the Invention
The present invention relates to a developing device for developing electrostatic latent images formed on the surface of a latent image carrying member using a two-component developing material.
2. Description of the Related Art
In recent years, small particle-diameter toners have been actively developed to produce highly detailed images in copying apparatus and printers using electrophotographic methods.
Toner increases its surface area per unit weight the smaller the particle diameter, and the amount of the electrical load of the individual toner particles increases, which tends to reduce image density.
There are a number of methods to counteract this tendency, such as a method wherein the developing potential is increased to increase the electrostatic adhesion force of the toner on the electrostatic latent image carrying member, and a method wherein the ratio (speed ratio) of the speed of movement of the developer relative to the speed of movement of the electrostatic latent image carrying member to increase the amount of developing material in contact with the electrostatic latent image carrying member per unit time.
The former method, however, has certain disadvantages inasmuch as it increases the amount of ozone produced by charging, as well as problems of carrier adhesion and fatigue of the electrostatic latent image carrying member, whereas the latter method has certain disadvantages inasmuch as line image reproducibility is reduced, and toner scattering increases. Another method increases the weight content of the toner relative to the carrier (hereinafter referred to as "toner density"), which produces certain disadvantages such as toner scattering via inadequate charging, and carrier fatigue.